I read with interest the published article by Ranjbar Kermani et al. (1). Genotyping of hepatitis C virus (HCV) is important, which provides information about strain variation and characteristics of virus during the treatment and the therapy response rate (2). In addition, it is of epidemiologic value because it sheds light on whether prevalent HCV strains are similar to that endemic ones in a certain region, such as those in the Middle East countries (3, 4). The study by Ranjbar Kermani et al. (1) in low sample size but the result in injecting drug users (IDUs) was interesting. This study indicates that the dominant HCV genotypes among patients were 3a and 1a (1). Most of studies in Iran showed that the dominant genotype was1, which is more common than the other genotypes (2, 4, 5). It may be related to their study on IDUs group. Zahedi et al. reported similar data with dominancy of genotype 3 in patients with a history of heroin abuse (6). Hosseini-Moghaddam et al. reported the genotype 3a as a more common genotype in patients underwent hemodialysis in Tehran (7).

In comparison with studies made in Yemen, Kuwait, Iraq, and Saudi Arabia, the most common genotype was type 4 (8). However, subtype 1b in Turkey or the western border of Iran and subtype 3a in Pakistan or eastern border of Iran are more prevalent (3). Genotyping was performed using type-specific primers (1) and they did not report any case with mixed genotype. It was related to the limitation of their method, in the other studies from Tehran, mixed HCV genotypes were also found in 2.5% of cases (2). Ranjbar Kermani et al. did not report any data about the relationship between age and distribution of HCV genotypes (1). Jahanbakhsh Sefidi et al. reported that subtype 1a was the most frequent genotype in patients over 40 years of age and subtype 3a was the most frequent ones in patients younger than 40 years old (2). It seems that distribution pattern of HCV genotypes has changed during recent years and today the infection with genotype 3a is increasing among IDUs and general population with HCV infection (9).